1. Field of the Invention
This invention relates generally to an adjustable vehicle shock absorber and, more particularly, to structure whereby the damping characteristic of a shock absorber is easily adjustable during operation.
2. Description of the Prior Art
Vehicle shock absorbers or dampers for hydraulically damping suspension excursions of a vehicle unsprung mass have been proposed with internal structure to change or adjust the shock absorber's damping characteristic so that optimum ride and handling can be achieved over a variety of surfaces. In some, adjustment requires relative rotation between a piston and rod assembly and a cylinder tube which is only accomplished when at least one end of the shock absorber is detached from the vehicle. In others, adjustment is effected without detachment from the vehicle through bulky and cumbersome auxiliary housings which complicate the structure and consume valuable space not readily available in vehicle suspension environments. In still others, adjusting structure is mounted directly on a piston and rod assembly of the shock absorber which assembly is normally attached to the sprung mass. Of these latter type structures, some have axially movable metering rods which progressively open and close orifices in passages between the rebound and compression chambers and some have rotatable control shafts which move valve plates for progressive covering and uncovering of bypass orifices between the compression and rebound chambers. Each of these structures, however, has a movable element with significant pressure unbalanced areas subjected to high working pressures during vehicle operation which could render it difficult or impossible to effect adjusting movement of the element under all vehicle operating conditions. A damper according to this invention includes novel structure whereby the damping characteristic of the unit is easily adjustable under all vehicle operating conditions.